Phytogeographic studies on Dominica, Lesser Antilles

S. R. Hill

Dominica, a small tropical volcanic oceanic island 45 km long and 24 km wide located between the French islands of Guadeloupe and Martinique, possesses a tremendous variety of altitudinal and moisture gradients. Vegetation varies from wet cloudforest on the high (1200-1435 m) mountaintops to dry desert scrub along the dry Caribbean coast. Since 1990, in cooperation with the Division of Forestry and Wildlife on Dominica, Dr. Hill has studyed and provided recommendations on various aspects of the flora, including the location and habitat mapping of individual species, the conservation of rare plants and plant communities, the newly introduced (generally exotic) species and their possible dispersal routes to the island, and environmental changes that may affect the survival of the vegetation. Data from this island may reflect more widespread trends in the dispersal and survival of species colonizing oceanic islands, the effects of global warming, and the effects of human activities on tropical rainforest and dry forest plant communities.

Studies of threatened and endangered plants of Illinois

S. R. Hill

In cooperation with the Illinois Endangered Species Protection Board (IESPB), population data are being compiled on several state and federally listed plant species in selected areas of Illinois. In 1999, research focused on the Cache River Floodplain in Alexander and Union counties, upland prairies in Cass and Morgan counties near the Illinois River, and the unusual and scarce dolomite prairies in and near the Midewin National Tallgrass Prairie site near Joliet. Of immediate concern is the location of natural populations of declining species and the development of plans to assist in their recovery or survival and for their introduction to restored environments. Compilation of information on the past and present vegetation and threatened and endangered plant species in Critical Trends Assessment Project areas of Illinois also continues. In 1999, reports were prepared on the living plant resources of the Prairie Parklands Assessment Area, a 945,000 acre site in portions of eight Illinois counties (Cook, Ford, Grundy, Kankakee, Kendall, La Salle, Livingston, Will) and for the DuPage River Assessment Area, a 238,000 acre site in portions of six Illinois counties (Cook, DuPage, Grundy, Kane, Kendall, Will). In 2000, a report will be prepared on the nearly 3 million acre Lower Sangamon River Assessment Area, containing all or parts of 15 central Illinois counties.

Monitoring the federal endangered species Dalea foliosa (Fabaceae) at Midewin National Tallgrass Prairie

B. Molano-Flores

Long-term monitoring of a population of the endangered species Dalea foliosa found in the dolomite prairie of the Midewin National Tallgrass Prairie was continued in 1999. At the request of the US Fish and Wildlife Service, a report was submitted describing the status of D. foliosa at the site. The reproductive output (i.e. fruit and seed set) of the population was also determined.

Temporal dioecism in a prairie species: Eryngium yuccifolium Michx. (Apiaceae)

B. Molano-Flores

Temporal dioecism is a synchronized flowering sequence with minimal overlap between the pistillate and staminate phases of an individual plant. This strategy allows pollen to be shed before stigmas become receptive, minimizing geitonogamous pollinations and maximizing outcrossing. This condition was studied in Eryngium yuccifolium, a tallgrass prairie perennial species. As a temporal dioecious species, E. yuccifolium exhibits the following: 1) even with an extended pistillate phase, stigmas only become receptive after the anthers have shed pollen and dehisce, 2) synchronized flower heads, 3) numerous flower heads visited by generalist pollinators, and 4) hand pollinations indicate some degree of self-compatibility. Finally, open and caged pollinations and high pollen-ovule ratios indicated that the species is xenogamous. This study also found high fruit and seed sets (close to 90%) for E. yuccifolium. However, intense herbivory by the larva of a gelechiid moth significantly reduced the reproductive output of the species by destroying 40-60 % of flowers and fruits. The results of this study indicate that temporal dioecism can enhance outcrossing and potentially can explain the high fruit and seed set for E. yuccifolium.

What can happen to heterostylous species in prairie restorations?: The case of Lithospermum canescens (Boraginaceae)

B. Molano-Flores

In distylous species, two flower morphs (pin and thrum) are found, and the proportion of these flower morphs is predicted to be 1:1. However, several studies have found that one flower morph is more abundant than the other. Under these circumstances, pollen flow may be reduced or biased, which could compromise the reproductive output of the species. In this study Lithospermum canescens, a distylous prairie species, was examined to determine 1) whether its flower morphs occur in a 1:1 proportion; and 2) whether flower morph proportion is related to population size. Seventeen Illinois populations of L. canescens were studied. No significant differences in the proportion of flower morphs were found, nor was there a significant relationship between population size and flower morph. However, when only small populations were analyzed, a significant relationship between population size and one of the flower morphs was found. This information can be applied to restored populations of L. canescens. Because the population size of this species in prairie restorations is small, particular attention may be needed to ensure that an equal proportion of flower morphs is maintained to increase the likelihood of successful restoration.

Reproductive biology of Lobelia spicata, a prairie species

B. Molano-Flores

In this project, several techniques (i.e. flower phenology, breeding system, pollen-ovule ratios, etc.) are being used to determine the reproductive biology Lobelia spicata. Preliminary results suggest that Lobelia spicata is a gynodieciuos xenogamous self-compatible species and is pollinated by small bees.

Assessment of the reintroduction potential of federally endangered and threatened plant species to managed sites in Illinois

L. R. Phillippe, S. M. Gehlhausen, K. R. Robertson, J. E. Ebinger

The overall goal of this project is to examine protected sites, primarily state owned and managed, and attempt to identify those suitable for the reintroduction of Federally listed species. These species include: Asclepias meadii (Mead's Milkweed), Boltonia decurrens (Decurrent False Aster), Dalea foliosa (Leafy Prairie Clover), Hymenoxys herbacea (Lakeside Daisy), Isotria medeoloides (Small Whorled Pogonia), Lespedeza leptostachya (Prairie Bush Clover), and Platanthera leucophaea (Prairie White Fringed Orchid). We did not include Cirsium pitcheri (Dune Thistle) in our study as there already is a recent report for this species. We conducted field reconnaissances to determine localities suitable for the introduction of these listed plant species back into native habitats. For each species, we summarized life history traits, natural community and ecological requirements, historic occurrences in Illinois, previous/current reintroduction efforts, and specific sites recommendations for reintroductions.

Effects of annual burning on populations of Cassia fasciculata (Fabaceae: Caesalpinioideae), with a review of its systematics and biology

K. R. Robertson, D. C. Gardner

Many people frequently encounter Cassia fasciculata (Partridge Pea) but have never taken the time to look at it closely and are unaware of many fascinating aspects of this species. The biology and systematics of C. fasciculata is well studied, at least as compared with other species native to Illinois. This information is widely scattered in the scientific literature. To make this information more widely available, a summary of the systematics, morphology, pollination, seed dispersal, and other interesting biological features was prepared. The field-based component of this study summarizes data collected during 18 years of observing the impact of fire on populations of C. fasciculata. Populations varied greatly from year to year. However, following burning, populations consistently increased compared with those populations in areas that were not burned. There was a mean population ratio of 5.2:1 for burned to unburned areas. This was further demonstrated by reversing the burned and unburned quadrats, which resulted in a reversal of population counts. Observations of changes in the abundance of other plant species during the study are noted.

Vascular flora of the Vermilion River Observatory,Vermilion County, Illinois

L.R. Phillippe, D.M. Ketzner, R.L. Larimore, J.E. Ebinger

The vascular flora of the Vermilion River Observatory, Vermilion County, Illinois, was studied during the 1996 - 1998 growing seasons. A total of 475 taxa were found: 13 ferns and fern-allies, 5 gymnosperms, 120 monocots, and 337 dicots. Families with the largest number of taxa included Asteraceae with 67 taxa, Poaceae with 53 taxa, and Cyperaceae with 33 taxa, of which 29 were members of the genus Carex. Two Illinois threatened species were encountered on the site, Carex communis (fibrous-rooted sedge) and C. willdenowii (Willdenow's sedge). Three forest communities (south-facing mesic upland forest, north-facing mesic upland forest, dry-mesic upland forest) were surveyed, and density (stems/ha), basal area (m2/ha), importance value, and average diameter were determined for each overstory species. The dry-mesic upland forest was dominated by various species of oaks and hickories. The mesic forested hillsides were dominated by oak species along with a more mesic component of Acer saccharum (sugar maple) and Fagus grandifolia (American beech).

Vascular flora of Momence Wetlands, Kankakee County, Illinois

L.R. Phillippe, W.C. Handel, S. Horn, J.E. Ebinger

The vascular flora of Momence Wetlands, Kankakee County, Illinois, was studied during the 1998 - 1999 growing seasons. 385 taxa were found: 6 ferns and fern-allies, 89 monocots, and 290 dicots. Families with the largest number of taxa included Asteraceae (59 taxa), Poaceae (44 taxa), and Cyperaceae (26 taxa), of which 17 were members of the genus Carex. This is the northernmost location in Illinois for four taxa generally associated with swamps in southern Illinois, Populus heterophylla L. (swamp cottonwood), Fraxinus profunda (Bush) Bush (pumpkin ash), Mikania scandens (L.) Willd. (climbing hempweed), and the state threatened Styrax americana Lam. (American storax). Three forest communities (wet floodplain, wet-mesic floodplain, dry-mesic upland) were surveyed, and density (stems/ha), basal area (m2/ha), importance value, and average diameter were determined for each overstory species. Wet floodplain forest was dominated by Acer saccharinum L. (silver maple); wet-mesic floodplain forest by Quercus bicolor Willd. (swamp white oak), Quercus palustris Muenchh. (pin oak), Ulmus americana L. (American elm), and Fraxinus pennsylvanica Marsh. (red/green ash); and dry-mesic upland forest by Quercus velutina Lam. (black oak) and Quercus alba L. (white oak). A wet-mesic prairie remnant dominated by Rubus flagellaris Willd.(Northern dewberry), Helianthus mollis Lam. (downy sunflower), Andropogon gerardii Vitman (big bluestem), and Solidago canadensis L. (tall goldenrod) was also surveyed.

Response of dry-mesic oak-hickory forest to annual fire in the Driftless Area of northwestern Illinois

W. C. Handel, S. Neuendorf

An effort to restore several prairie and dry-mesic oak savanna communities have been underway in the Wisconsin Driftless Division of northwestern Illinois. One area within the Mississippi Palisades state park is being quantitatively sampled to measure how the herbaceous and shrub layers respond to fire. The area is a dry-mesic black and white oak forest on a southwest-facing slope. Prairie vegetation occurs at the bottom of the slope and along the ridge above the forest. Aerial photography from 1964 show that this area was more open with small areas of prairie scattered along the slope. The goal is to control exotic vegetation, such as garlic mustard and to encourage fire dependent grasses and forbs. Baseline data were gathered in summer of 1998 before the first controlled burn. The site was burned during the spring of 1999 and the area was sampled in September of 1999. After the first burn, some fire dependant species increased in the herbaceous layer and the fire top-killed about 80-90% the shrub layer.

Reference data collection for sand prairie restoration

A. J. Symstad

Lost Mound Wildlife Unit, also known as the Savanna Army Depot, has approximately 4,000 acres of sand prairie and savanna degraded from decades of heavy grazing, fire suppression, and military construction. After the military mission at Lost Mound ends in March 2000, part of the land will be used for prairie restoration research. Some of the key information needed when doing any kind of ecological restoration is what the structure and composition of the plant community are like in a healthy example of the ecosystem being restored. This information provides a reference point to help determine what efforts are needed to restore a degraded ecosystem. During the summer of 1999 data were compiled on the structure and composition of two relatively intact sand prairies, Ayers Sand Prairie Nature Preserve and Thomson Sand Prairie, near Lost Mound. These data will be compared to similar data collected at restoration research sites in Lost Mound in 2000 to determine what types of research will provide useful information for designing a long-term recovery plan for the sand prairies at Lost Mound.

Hudsonia tomentosa and associated plant communities

A. J. Symstad

Hudsonia tomentosa Nutt. (beach heather) is a state-endangered, mat-forming shrub that grows in areas of open sand. In the summer of 1999, a monitoring program was re-established for this plant at Ayers Sand Prairie Nature Preserve, one of four or five locations of this plant in the state. Monitoring during the 1980's showed that the plant was declining, probably due to a variety of factors including drought, fires, and encroaching prairie vegetation and trees. Many of the populations censused in the 1980's had declined significantly or disappeared in 1999. However, a large population that existed in the 1980's but was not monitored still exists at the site in a complex of blowouts within the prairie matrix. In this population, monitoring plots were established to track how the Hudsonia population and the plant communities that grow with and around it change through time and in response to events such as fire and drought.

Vegetation patterns associated with Ceanothus americanus in tallgrass prairie remnants

J. B. Taft, A. Symstad , J. Dawson (NRES, University of Illinois)

This research is designed to evaluate the role of nitrogen-fixing shrubs, with a focus on the actinorhizal species Ceanothus americanus, in community organization in tallgrass prairie. Specific goals are to examine: 1) patterns of nitrogen availability in soils associated with two native nitrogen-fixing shrubs, 2) species composition and diversity patterns associated with nitrogen-fixing shrubs, 3) light and temperature variability related to these prairie shrubs, and 4) germination success and seedling survival of two nitrogen-fixing shrubs in different prairie patches. In a preliminary study, vegetation associated with Ceanothus americanus individuals had lower diversity and greater C3 graminoid species abundance, relative to C4 species, than prairie vegetation not associated with C. americanus individuals. These results are consistent with the findings of research examining vegetational responses to experimentally increased available nitrogen in tallgrass prairies. This study will attempt to confirm the vegetation patterns found in the pilot study, test for similar results from an additional nitrogen-fixing shrub and a non-nitrogen fixing shrub, and expand on methods to understand the mechanisms behind these patterns.

Comparative analysis of community integrity indices in habitat restorations

J. Taft, C. Hauser, K. Robertson.

A research program is proposed for Nachusa Grasslands to examine indices developed to measure community-level properties related to community integrity. Indices chosen for comparison are Species Richness Index and related indices, and Floristic Quality Assessment and related indices. These indices were developed as tools for discriminating vegetation that differs qualitatively both spatially and temporarily and thus can be used to make spatial and time-series comparisons. Hypotheses will be tested regarding comparisons among these indices and to more standard community-level metrics, response of indices to different spatial scales, importance of quantitative data, and sensitivity to detecting qualitatively different units as determined by Illinois Natural Areas Inventory grading. In addition, methods for rapid assessments of vegetation will be tested against more rigorous methods to identify tools that have potential for application by a wide spectrum of skill levels among restoration practitioners.

Effects of prescribed fire and leaf-litter removal on a population of Collinsia violacea (Scrophulariaceae), an endangered species in Illinois

J. Taft , E. Smith (IDNR)

Three adjacent colonies of the annual Collinsia violacea occur in Illinois and these are disjunct from the primary range for the species west of Illinois. The main Illinois colony occurs in a small barrens habitat that appears to be undergoing vegetational changes, presumably as a result of a long fire-free period. The most salient example of change is the establishment of a subcanopy of sugar maples beneath an oak-dominated canopy. This study examines the effects of two possible management options for C. violacea: 1) applications of prescribed fire, to examine the effects of a standard barrens management tool on the population of C. violacea, and 2) the mechanical leaf litter removal, to examine the success of a possible species-level management option for C. violacea. Baseline data will be recorded for two consecutive years prior to treatments. Treatments will be replicated within one-meter2 blocks; for the prescribed burn study, an aluminum burn box will be used to contain the fire. Our hypothesis is that both treatments will result in more and larger populations compared with no treatment.

Gibbons Creek Barrens burn study

J. Taft

Barrens are one of the rarest and least studied community types in the Midwest and, due to fire absence, they continue to decline. This study, using baseline data from permanent plots, measures the response of the groundcover, shrub, and tree strata to prescribed fire. Fire is excluded from a nearby barrens providing a control site. The study area is near Herod, Illinois in Pope County. Following seven years of intensive monitoring and research, monitoring will be conducted at longer time intervals to detect long-term effects of fire management.

Flatwoods burn study

J. Taft

This study of a IDOT-owned post oak flatwoods near Mt. Vernon, Illinois measures the response of groundcover, shrub and tree strata to prescribed fire. Permanent plots were established and baseline and post-burn data from three prescribed fires have been collected for this site. Following seven years of intensive monitoring and research, monitoring will be conducted at longer time intervals to detect long-term effects of fire management.